Various transistors, as commonly-used devices in an electrical field, are applied widely. For products manufactured in mass in an electronic industry, such as various Thin Film Transistors (TFTs), Metal Oxide Semiconductor (MOS) transistors and the like which are widely used in a liquid crystal field at present, their various electrical characteristics are required being tested, in order to ensure performances required and a reliable quality as applied to an electronic apparatus. Currently, when a transistor is tested, generally a bias voltage characteristic of each single transistor is tested one-by-one and then a current of each transistor is tested. By taking a MOS transistor as an example, the bias state of the MOS transistor should be tested in some bias conditions generally, for example, in a case where a voltage of an electrode of the MOS transistor is fixed while voltages of the other two electrodes are changed. since the time taken for testing each transistor is long and a number of the transistors to be tested is large, a testing efficiency is very low, which greatly decreases efficiencies of the subsequent work flows. FIG. 1 illustrates a connection for a known circuit for testing transistor(s), wherein, by taking a NMOS transistor as an example, a drain of the NMOS transistor is connected to a power supply voltage Vd, its gate is connected to a gate control signal Vg, and its source is connected to a test terminal; depending on testing requirements, the voltages applied to the respective electrodes are changed so at to test the bias state of the NMOS transistor. Since only one transistor can be tested regarding its bias state each time, the testing efficiency is very low. Similarly, when bias voltage characteristics of transistors are tested, in general, the transistors are tested respectively. By taking the NMOS transistor as an example, the drain of the NMOS transistor is connected to the power supply voltage Vd, its gate is connected to the gate control Vg, and its source is in a floating state, wherein the voltages applied to the corresponding electrodes are changed depending on the test requirements, so that the bias voltage state in which its source is in a floating state can be tested. Since only one transistor can be tested regarding its bias voltage state each time, the testing efficiency is very low.